Not all textbooks are the same. Here are two samples from Elementary/ Basic Mathematics textbooks. The Houghton Mifflin text (above) has many more visualizations [data bars] here to assist in teaching how to add fractions. The Scott Foresman text below has fewer visuals, but more numerical-text practice.
To evaluate supplemental materials for your visual-spatial child; seek out those with many visuals, illustrations & diagrams.
In the Adult Educational array of curriculum currently available; few if any visual offerings exist. It is ok to look to supplement your resources with a more ‘elementary’ style of textbook like those shown here to use with an adult student. The goal is to help them learn… if they learn more easily and quickly when visualizations are available.. then find them and use them.
